Positively stimulates PRMT1-induced protein argininedimethylated arginine methylation (PubMed:28040436). Promotescolorectal cancer cell malignancy (PubMed:28040436).{ECO:0000269|PubMed:28040436}. | Transcriptional repressor which forms a core componentof the circadian clock. The circadian clock, an internal time-keeping system, regulates various physiological processes throughthe generation of approximately 24 hour circadian rhythms in geneexpression, which are translated into rhythms in metabolism andbehavior. It is derived from the Latin roots 'circa' (about) and'diem' (day) and acts as an important regulator of a wide array ofphysiological functions including metabolism, sleep, bodytemperature, blood pressure, endocrine, immune, cardiovascular,and renal function. Consists of two major components: the centralclock, residing in the suprachiasmatic nucleus (SCN) of the brain,and the peripheral clocks that are present in nearly every tissueand organ system. Both the central and peripheral clocks can bereset by environmental cues, also known as Zeitgebers (German for'timegivers'). The predominant Zeitgeber for the central clock islight, which is sensed by retina and signals directly to the SCN.The central clock entrains the peripheral clocks through neuronaland hormonal signals, body temperature and feeding-related cues,aligning all clocks with the external light/dark cycle. Circadianrhythms allow an organism to achieve temporal homeostasis with itsenvironment at the molecular level by regulating gene expressionto create a peak of protein expression once every 24 hours tocontrol when a particular physiological process is most activewith respect to the solar day. Transcription and translation ofcore clock components (CLOCK, NPAS2, ARNTL/BMAL1, ARNTL2/BMAL2,PER1, PER2, PER3, CRY1 and CRY2) plays a critical role in rhythmgeneration, whereas delays imposed by post-translationalmodifications (PTMs) are important for determining the period(tau) of the rhythms (tau refers to the period of a rhythm and isthe length, in time, of one complete cycle). A diurnal rhythm issynchronized with the day/night cycle, while the ultradian andinfradian rhythms have a period shorter and longer than 24 hours,respectively. Disruptions in the circadian rhythms contribute tothe pathology of cardiovascular diseases, cancer, metabolicsyndrome and aging. A transcription/translation feedback loop(TTFL) forms the core of the molecular circadian clock mechanism.Transcription factors, CLOCK or NPAS2 and ARNTL/BMAL1 orARNTL2/BMAL2, form the positive limb of the feedback loop, act inthe form of a heterodimer and activate the transcription of coreclock genes and clock-controlled genes (involved in key metabolicprocesses), harboring E-box elements (5'-CACGTG-3') within theirpromoters. The core clock genes: PER1/2/3 and CRY1/2 which aretranscriptional repressors form the negative limb of the feedbackloop and interact with the CLOCK|NPAS2-ARNTL/BMAL1|ARNTL2/BMAL2heterodimer inhibiting its activity and thereby negativelyregulating their own expression. This heterodimer also activatesnuclear receptors NR1D1/2 and RORA/B/G, which form a secondfeedback loop and which activate and repress ARNTL/BMAL1transcription, respectively. PER1 and PER2 proteins transport CRY1and CRY2 into the nucleus with appropriate circadian timing, butalso contribute directly to repression of clock-controlled targetgenes through interaction with several classes of RNA-bindingproteins, helicases and others transcriptional repressors. PERappears to regulate circadian control of transcription by at leastthree different modes. First, interacts directly with the CLOCK-ARTNL/BMAL1 at the tail end of the nascent transcript peak torecruit complexes containing the SIN3-HDAC that remodel chromatinto repress transcription. Second, brings H3K9 methyltransferasessuch as SUV39H1 and SUV39H2 to the E-box elements of the circadiantarget genes, like PER2 itself or PER1. The recruitment of eachrepressive modifier to the DNA seems to be very preciselytemporally orchestrated by the large PER complex, the deacetylasesacting before than the methyltransferases. Additionally, large PERcomplexes are also recruited to the target genes 3' terminationsite through interactions with RNA-binding proteins and helicasesthat may play a role in transcription termination to regulatetranscription independently of CLOCK-ARTNL/BMAL1 interactions.Recruitment of large PER complexes to the elongating polymerase atPER and CRY termination sites inhibited SETX action, impeding RNApolymerase II release and thereby repressing transcriptionalreinitiation. May propagate clock information to metabolicpathways via the interaction with nuclear receptors. Coactivatorof PPARA and corepressor of NR1D1, binds rhythmically at thepromoter of nuclear receptors target genes like ARNTL or G6PC.Directly and specifically represses PPARG proadipogenic activityby blocking PPARG recruitment to target promoters and therebyinhibiting transcriptional activation. Required for fatty acid andlipid metabolism, is involved as well in the regulation ofcirculating insulin levels. Plays an important role in themaintenance of cardiovascular functions through the regulation ofNO and vasodilatatory prostaglandins production in aortas.Controls circadian glutamate uptake in synaptic vesicles throughthe regulation of VGLUT1 expression. May also be involved in theregulation of inflammatory processes. Represses the CLOCK-ARNTL/BMAL1 induced transcription of BHLHE40/DEC1 and ATF4.Negatively regulates the formation of the TIMELESS-CRY1 complex bycompeting with TIMELESS for binding to CRY1.{ECO:0000250|UniProtKB:O54943}. |